Perl: Using readdir and . ..

cramer · 09-09-2006, 11:32 PM

Just a simple question. Anyway to keep the . and .. from showing up in an array when I use readdir?

ghostdog74 · 09-09-2006, 11:55 PM

An example

Code:

@dirs = readdir(DIR) or die .....
closedir(DIR);
foreach $d (dirs) {
    next if ($d eq "."); 
    next if ($d eq "..");
    ....
    ....

chrism01 · 09-12-2006, 02:34 AM

Or slightly more compact / perlish

next if $file =~ /^\.\.?$/;

makyo · 09-13-2006, 10:52 AM

Hi.

The part of this topic relating to regular expressions reminded me of the section in Conway's Perl Best Practices. If I understand Conway, he would suggest writing the RE like this:

Code:

next if $i =~ m{ ^ [.] [.]? $ }xms;

I think his approach is useful: balance readability and maintainability with speed. I cannot say that my fingers are yet familiar typing the braces (especially for multi-line patterns) and then the xms modifiers after every match expression, but it's not as foreign as it once was. It is clearly more typing, but I agree that the single-character classes are more readable compared to leaning toothpicks.

In addition to readability, he also writes about issues affecting performance.

If one does a lot of perl, I think it's a useful book, particularly if one is writing code that someone else may need to maintain. Many people in the local perl-mongers group seem to like it ... cheers, makyo
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ghostdog74 · 09-13-2006, 07:21 PM

I would think if its for readability , no regular expression is better.

treii28 · 04-23-2008, 11:34 AM

Quote:

Originally Posted by chrism01

Or slightly more compact / perlish

next if $file =~ /^\.\.?$/;

next if $file =~ /^\.{1,2}$/;

chrism01 · 04-23-2008, 07:04 PM

Well, given it's Perl, TMTOWTDI. As it happens, I got my version from the Perl CookBook (Recipe 9.5), and if it's good enough for them, it's def good enough for me

bigearsbilly · 04-24-2008, 04:25 AM

even more perlish?

Code:

@dirs = grep { !/^\.\.?/ } readdir(DIR);